IEC 60268-3:2018 pdf download

IEC 60268-3:2018 pdf download.Sound system equipment – Part 3: Amplifiers
1 Scope
This part of IEC 60268 applies to analogue amplifiers, and the analogue parts of analogue/digital amplifiers, which form part of a sound system for professional or household applications. It specifies the characteristics that should be included in specifications of amplifiers and the corresponding methods of measurement. NOTE The methods of measurement for digital amplifiers and similar equipment are given in IEC 61 606 [1 ] 1 . In general, the specified methods of measurement are those which are seen to be most directly related to the characteristics. This does not exclude the use of other methods that give equivalent results. In general, the methods are based on the simplest measuring equipment which can provide useful results. This does not exclude the use of more complex equipment that can give higher accuracy and/or allow automatic measurement and recording of results. Rated conditions and standard measuring conditions are specified in order to allow measurements to be reliably repeated.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60065:201 4, Audio, video and similar electronic apparatus – Safety requirements IEC 60268-1 :1 985, Sound system equipment – Part 1: General IEC 60268-1 :1 985/AMD1 :1 988 IEC 60268-1 :1 985/AMD2:1 988 IEC 60268-2:1 987, Sound system equipment – Part 2: Explanation of general terms and calculation methods Amendment 1 :1 991 IEC 6041 7:2002, Graphical symbols for use on equipment – 12-month subscription to regularly updated online database comprising all graphical symbols published in IEC 60417 IEC 60958:201 6 (all parts), Series, Digital audio interface
3 Terms, definitions and rated values
3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp 3.1.1 class A class of operation in which the current in each active device supplying the load current is greater than zero throughout each cycle of the signal for all values of load current up to, and including, the value determined by the rated output power or voltage and the rated load impedance 3.1 .2 class B class of operation in which the current in each active device supplying the load current is equal to zero for exactly one-half of each cycle of load current Note 1 to entry: In common usage, the term Class B is extended to the case where current flows for slightly more than one half-cycle. Note 2 to entry: Classes G and H are modifications of class B with improved efficiency. 3.1.3 class AB class of operation in which the current in at least one of the active devices supplying the load current is zero for some part of each cycle of load current for some range of values of load current not exceeding the value defined by the rated output power or voltage and the rated load impedance NOTE 1 Total harmonic distortion and (distortion-limited) output voltage or power are interdependent. Both cannot be taken as rated conditions simultaneously because normally a given sample amplifier produces less than rated total harmonic distortion at rated output voltage or power. NOTE 2 If the power supply frequency is critical, it is also a rated condition. To obtain the correct conditions for measurements, the values for the above-mentioned rated conditions shall be taken from the manufacturer’s specification. These values themselves are not subject to measurement but they constitute the basis for measuring the other characteristics. Methods of measurement for these other characteristics are given in this document and the manufacturer is either required or permitted to state ‘rated values’ for these characteristics in the specification of the equipment.